During the past few weeks, a lot of behind-the-scenes work has been progressing, such as obtaining permits for the project from the U.S. Corps of Army Engineers, the U.S. Coast Guard and Kentucky and Indiana environmental agencies, said Aaron Stover, project manager for Michael Baker Jr. Inc., the architectural firm hired for design review on the project.

Stover said Monday that crews should start setting up the staging areas on both sides before Jan. 1. In Milton, there will be two staging areas. One, located between the bridge and the old well heads, also will be the site for the temporary accessway to carry motorists across the bridge, Stover said.

He said landowner Kenneth McCoy is leasing adjacent property there for large staging area, where a dock will be extended from the riverbank toward the middle of the river. The dock will provide access to the barges that will bring supplies and equipment, as well as the barges on which the new trusses will be built and moved, Stover said.

Eventually, that area also will be where materials and large equipment, including cranes, will be stored.

Stover said the temporary accessway on the Milton side will extend through the field between the Milton boat ramp and the existing bridge from Ferry Street. The route will include a 90-degree turn from Ferry Street and another 90-degree turn onto the bridge.

Stover said the turns are comparable to those used by motorists now, but said it shouldn’t be an issue for large trucks because the 15-ton weight limit placed on the span last year will remain until the new span is completed. He said Walsh engineers are working to make the accessway maneuverable by buses and other large vehicles that will still need to use the bridge.

Construction on the accessways is to begin in April, according to a timeline issued by project officials on Tuesday, Dec. 7. The first five-day closure will occur in mid-July, when the new accessways will be connected to the existing span.

On the Indiana side, Stover said traffic will make a 45-degree right turn off the bridge, down a retaining wall and onto Vaughn Drive, then turn on Ferry Street to Hwy. 56.

Additionally, Walsh is considering a plan to set up ferry service from the Milton boat ramp to Madison for ambulances and other emergency vehicles during each of the five-day bridge closures.

In July, crews are expected to begin building the new permanent approaches and the temporary piers, which will be located just a few feet downstream from the existing bridge.

In September to May 2012, crews will begin assembling the new trusses. That phase is expected to be completed in May 2012, when project leaders plan to shift traffic over onto the new bridge. At that point, demolition of the old span will begin and last through July 2012. Once that is completed, crews will work to widen the tops of the existing piers through early September.

At that point, the crossing will be closed for the second five-day period, as the new span is moved from the temporary piers to the existing piers and connected to the permanent access ramps.

According to officials, the temporary piers will be built to modern specifications, capable of carrying the same amount of traffic and and strong enough to withstanding barge impact.

Stover said Walsh is considering using small explosive charges to bring the old bridge trusses down.

However, he said, because the equipment will be on site, the company may use cables and jacks to lower sections of the trusses onto a barge – a reverse of the process that will be used to place the new trusses onto the temporary piers.

“They have to take into consideration worker safety and water levels,” Stover said. “It might be quicker to use explosives, but [by lowering the trusses] they won’t have to worry about digging it out of the river.”

All in all, Stover said he and the Baker firm are excited to be part of the project, which has caught worldwide attention for the anticipated innovations in bridge design and construction.

The project already has been written about in overseas engineering magazines and in U.S. publications, including “Roads and Bridges” and “Engineering News Record.”

“We expect that [attention] to continue, and probably to increase,” Stover said.